Smart Inverter Zero Droop Voltage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional voltage control methods in power distribution grids face challenges due to extreme voltage volatility at the edge of the grid, caused by increased penetration of distributed photovoltaic systems, leading to instability and reduced lifespan of primary assets, as existing Volt Var Control (VVC) tools struggle to accurately characterize voltage conditions and maintain tight voltage regulation.
Innovation Solution
Implementing smart inverters at the edge of the power distribution network that can absorb or inject VARs based on a reference Q value, using a controller with a processor and memory to adjust reactive power output, thereby maintaining voltage within specified limits and preventing infighting between inverters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional VVC tools are used to control voltage, then voltage regulation is attempted, but voltage volatility at the edge of the grid cannot be accurately characterized and controlled
Solution Approach 1:
The smart inverter autonomously measures local voltage conditions and independently determines reactive power adjustments without requiring complex centralized characterization of grid-wide voltage conditions. Each inverter serves itself by locally detecting voltage deviations and self-regulating its reactive power output accordingly.
Solution Approach 2:
The system changes the control parameter from attempting to characterize overall voltage conditions to simply responding to local voltage deviations. The reactive power reference Qref is dynamically adjusted based on the sign and magnitude of the voltage deviation ev, transforming the control approach from measurement-intensive to response-based.
2Productivity
If multiple inverters are deployed to increase capacity, then system capacity utilization improves, but infighting between inverters occurs causing instability
Solution Approach 1:
Each inverter operates with locally-specific control characteristics determined by its position on the feeder. The voltage deviation ev is measured locally at each inverter, and the reactive power response is tailored to local conditions rather than applying uniform control across all inverters, preventing coordination conflicts.
Solution Approach 2:
Each inverter applies only the necessary reactive power adjustment to correct its local voltage deviation, rather than all inverters attempting to fully correct the voltage simultaneously. This partial action approach prevents over-correction and infighting while maintaining overall voltage stability across the network.
3Manufacturing precision
If tight voltage regulation is maintained to meet ANSI standards, then voltage quality is improved, but the system becomes vulnerable to voltage volatility from distributed PV
Solution Approach 1:
The system dynamically adapts its reactive power output in response to changing voltage conditions caused by distributed PV generation. Rather than maintaining fixed voltage setpoints, the smart inverter continuously adjusts Qref based on real-time voltage deviations, enabling the system to adapt to volatile conditions while maintaining voltage within acceptable bounds.
Solution Approach 2:
The control system uses feedback from local voltage measurements to continuously adjust reactive power output. The voltage deviation ev is fed back into the control logic which modifies Qref accordingly, creating a closed-loop system that maintains tight voltage regulation while adapting to PV-induced volatility through continuous correction.
Data Source
AI summary
Systems and methods for controlling grid voltage include a distribution power network and one or more smart inverters at or near the edge of the distribution power network, each smart inverter configured to absorb or insert VARs to control the voltage based on a reference Q value, wherein the reference Q value is calculated by a reference Q calculator. A reference Q calculator includes a processor and a non-transitory computer readable memory with software embedded thereon, the software configured to cause the processor to receive a voltage measurement taken at or near the edge of a power distribution grid, a voltage band value, and a voltage set point value, determine a difference, ev, between the voltage measurement and the voltage set point, generate a new reference Q value if an absolute value of ev is greater than the voltage band value, and cause the smart inverter to either absorb or insert VARs depending on the sign of ev.